From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lists1p.gnu.org (lists1p.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2A761606A331 for ; Sat, 7 Nov 2026 23:00:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=H6YBZ2eP Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1xPpN3-0007l1-2Z; Sat, 07 Nov 2026 17:58:49 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1xPpN0-0007ju-Te for qemu-devel@nongnu.org; Sat, 07 Nov 2026 17:58:47 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1xPpMz-0002WV-55 for qemu-devel@nongnu.org; Sat, 07 Nov 2026 17:58:46 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1794092324; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Ed41uV7/MDec/L7nxah8JDQN7dNidJNpoC1RnOdFGOU=; b=H6YBZ2ePWaXPOYuGMgToPM8FtnvqAXRCkBCKn2P+sz/M+CX0hHnxKvUnW4zMkY7wqydT0B ZEKReHFds0YZJo4vHd9ZTdfJhmALe/1j1ZvsG+xIz4Lf+js/GDeX3L3UOs2z0rh6Rb4Uw8 KAPrIYA2Khhn5K043XD+v+Cs2a8pfI0= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-674-wT33DzpxPBmWO4BYcSE3oQ-1; Sat, 07 Nov 2026 17:58:42 -0500 X-MC-Unique: wT33DzpxPBmWO4BYcSE3oQ-1 X-Mimecast-MFC-AGG-ID: wT33DzpxPBmWO4BYcSE3oQ_1794092321 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 45CBE1956094; Sat, 7 Nov 2026 22:58:41 +0000 (UTC) Received: from eblake.csb (headnet04.pony-001.prod.iad2.dc.redhat.com [10.2.32.116]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id BB8D61956087; Sat, 7 Nov 2026 22:58:39 +0000 (UTC) From: Eric Blake To: qemu-devel@nongnu.org Cc: qemu-stable@nongnu.org, berrange@redhat.com, qemu-block@nongnu.org, Pierrick Bouvier Subject: [PATCH v2 1/3] docs: Mention security considerations for NBD Date: Sat, 7 Nov 2026 16:54:36 -0600 Message-ID: <20261107225834.778738-6-eblake@redhat.com> In-Reply-To: <20261107225834.778738-5-eblake@redhat.com> References: <20261107225834.778738-5-eblake@redhat.com> X-Archived-By: MIME-Version: 1.0 Content-type: text/plain Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Received-SPF: pass client-ip=170.10.133.124; envelope-from=eblake@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: 5 X-Spam_score: 0.5 X-Spam_bar: / X-Spam_report: (0.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, MARKETING_PARTNERS=0.001, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_SBL_CSS=3.335, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Archive: List-Post: List-Help: List-Subscribe: , Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI, MARKETING_PARTNERS,SPF_HELO_PASS,SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 Document a policy that NBD connections should strongly consider using TLS and x509 certificates to filter out untrusted clients. If a malicious server or client can trigger a QEMU assertion failure on a plaintext connection, but can be trivially mitigated by enabling TLS to weed out untrusted partners that would violate the protocol in the first place, then I prefer to treat the bug as a lower-priority issue, which our policy states can be fixed without an embargo. Signed-off-by: Eric Blake --- docs/system/security.rst | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/docs/system/security.rst b/docs/system/security.rst index e211fdd2344..7b422d51472 100644 --- a/docs/system/security.rst +++ b/docs/system/security.rst @@ -320,3 +320,24 @@ encryption and authorization control policy on client connections. In summary, the monitor console is considered a privileged control interface to QEMU and as such should only be made accessible to a trusted management application or user. + +Block device network protocols (NBD, NFS, etc.) +''''''''''''''''''''''''''''''''''''''''''''''' + +When using QEMU to access remote storage over a network (such as QEMU +acting as an NBD or NFS client) or to provide remote storage access +(such as QEMU acting as an NBD server), it is important to realize +that an unencrypted connection can allow an external process a +potential attack vector over the network port. When possible, QEMU +should be configured to require TLS to prevent a man-in-the-middle +attack, as well as use x509 client certificates with the +tls-creds-x509 object set with 'verify-peer=on' to check that the peer +is allowed to connect. It may also be worth using 'tls-authz' to +filter which certificates are allowed if the CA issues certs more +broadly. + +Proper hardening of network connections can prevent the use of +untrusted clients, and is therefore a factor when considering whether +a malicious network partner that intentionally violates the +communication protocol to trigger a QEMU bug can be treated as a lower +priority bug. -- 2.56.0